In today's society, secondary batteries are widely used in various devices including portable electronic products such as laptop computers, cameras, cellular phones, MP3s as well as cars, robots, satellites or the like. These secondary batteries are extensively used due to their great advantages of being able to repeatedly charge and discharge and store energy.
In particular, with the gradual exhaustion of carbon energies, such as oil, coal and natural gas, and the recent increased interest in the environment, efficient energy consumption has become an important issue. Therefore, many efforts have been made to improve the efficiency of energy consumption and a smart grid system is an example of a result of these efforts.
A smart grid system is an intelligent electric grid system which incorporates an information and communication technology into the production, transfer and consumption process of power, thereby inducing the interaction of power supply and consumption and thus enhancing the efficiency of electricity usage. The amount of electric energy used by a consumer may not always be constant and can frequently change. For example, in the summer time, the electric energy consumption can increase rapidly due to the use of an air conditioner in the afternoon and rapidly decrease later on in the evening. Like above, the amount of electric energy consumed may not always be constant and can frequently change, and even if the power supply is controlled to some degree, it is realistically impossible to meet the varying electric energy consumption amount. Accordingly, the imbalance of the power supply and electric energy consumption may cause an excess or deficiency of the power supply. In order to solve such a problem, a smart grid system checks for the power status in real time to flexibly control the power supply, and a power storage battery pack for storing power is an important component in constructing such a smart grid system. In other words, since a smart grid system is configured to store surplus power when power consumption is low and supply the stored power with supply power to consumers when power consumption is high, a power storage battery pack for storing power is important for the smart grid system.
Such a power storage battery pack may be used in various fields as well as in a smart grid system. For example, a power storage battery pack may be used in electric vehicle (EV) charging stations that store a great amount of power needed to supply EVs.
A power storage battery pack should be provided with a plurality of battery modules to have a capacity larger than a general battery pack used in portable electronic products as well as other various kinds of devices. The plurality of battery modules are received as a multi-layered stack for their space efficiency and connectivity. However, if the plurality of battery modules are stacked without using any kind of container, the weight of the battery modules positioned at the upper layer is directly loaded onto the battery modules positioned at the lower layer, so that the static deflection or permanent deformation of the battery module may occur. In other words, the battery modules are precariously stacked, and the safety of the battery modules is threatened due to the pressure and deformation thereof. Accordingly, a power storage battery pack is conventionally provided with a battery container for receiving a plurality of battery modules. Such a battery container is referred to as a battery holder, a battery tray, or a battery rack.
FIG. 1 is a perspective view schematically showing a conventional battery container.
As shown in FIG. 1, a conventional battery container is configured with a structure, such as an L-type frame 20. That is, a plurality of L-type frames 20 internally divides the battery container into multiple layers by welding or screw-fixing, similar to a bookshelf, and battery modules 10 are received in each layer. The battery container as described above is configured to support the bottom of the battery modules 10 by using a lower structure, such as the L-type frame 20 or a separate bottom plate (not shown).
In the conventional battery container, each structure placed at the bottom of the battery modules should have high strength and be strongly coupled to another structure in order to stably receive the battery modules 10. If not, the battery container may be deformed or destroyed due to the weight of the battery modules 10, and this further causes the battery modules 10 to break. Accordingly, the conventional battery container needs to increase the thickness of its structure or be further provided with a new structure, thereby becoming more complicated.
Moreover, in order to ensure a predetermined or larger amount of supporting force, the structures placed at the bottom of the battery modules should be strongly coupled to other structures of the battery container in the conventional battery container. However, this generates another problem when the battery container changes its shape. For example, if a battery container is configured with three separate layers as shown in FIG. 1, one or more layers are added by replacing four existing L-type frames 20, which are vertically standing in the container, with four new L-type frames 20 which have a height higher than the existing L-type frames. To achieve this, after pulling out the received battery modules 10 from the battery container, it must go through a complicated process of having to not only disassemble the existing L-type frames 20, but also assemble the new L-type frames 20. This complicated process of having to disassemble and assemble the L-type frames 20 must also be performed when having to remove one layer from a battery container having three separate layers, as shown in FIG. 1. Accordingly, the conventional battery container has a problem in that the structural change, which is required for adding a new battery module 10 or removing the existing battery module 10, is complicated and difficult.